A few corrections to the SDK betas post now that the releases are out and the claims can be checked against them.

• Install opt-in: "Installing any of the four aforementioned SDKs without explicitly requesting a pre-release still resolves to a stable version" is not true for TypeScript. The v2 packages (@modelcontextprotocol/server and friends) are new package names whose only release is 2.0.0-beta.1, and npm's latest tag points at it, so a bare npm install @modelcontextprotocol/server gets the beta. The paragraph now scopes the stable-resolution claim to Python, Go, and C#, and says installing the new TypeScript packages is itself the opt-in.
• Wire behavior on upgrade: the transport-level opt-in described in that paragraph applies to TypeScript and Go, but Python and C# take the opposite default. A Python v2 server answers both protocol revisions from one endpoint as soon as you upgrade, and the C# preview's HTTP transport defaults to stateless mode. Added a sentence saying so.
• Major versions: added a sentence making explicit that the v2 SDK lines are new major versions, so moving your own code onto them is a breaking change you take on your own schedule, separate from anything that happens on July 28.
• Python framing: the post presented the schema-free decorator server as new in v2, but the example is v1's FastMCP quickstart almost verbatim, and that API shipped in v1.2.0. Reworded to say the decorator API carries over ("FastMCP becomes MCPServer") and dropped "the API got smaller", which does not hold up against the actual v2 surface.
• Routing headers: Mcp-Name does not ride on every request, only on requests that name a tool, resource, or prompt (tools/call, resources/read, prompts/get) per SEP-2243. A gateway configured from the original sentence would reject conforming traffic.
• Release notes: not every SDK's release notes list exactly which SEPs are covered (the TypeScript notes do not mention SEPs at all), so that clause is softened.
• Link fix: the MRTR link was the post's only http:// URL; now https://.

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